The procedure is to fork OpenMW/openmw on github. That create a local clone of this fork on your machine, add the files there, commit and push to your fork on github. After that you only need to send a pull request via the github web interface.

The png files go into files/opencs.

The svg files go into files/opencs/scalable.

Edit: Since this isn't overly urgent, let's give it a try with these icons. I'll await your pull request.

We need another set of icons of the same type (but a separate button) for cell marker, cell arrows and cell borders. But since only one of these is currently implemented and we don't know exactly yet how the other two will look, maybe we should wait with that.

Then we have the run button (start OpenMW from within OpenCS). We need that in two versions. One active/enabled (because of at least one usable debug profile available) and one inactive/disabled (because no usable debug profile is available).

Shouldn't that be handled by the toolkit? Not sure about Qt, but in GTK+ there's a sensitive=false property that takes care of that. Like this:

We could use the build-in functionality to indicate a disabled button, but I would prefer to give some hints about the problem (the icon should be big enough for that).

Besides, it's probably a better idea to kick off a debug profile setup dialog on pressing that button than disabling it altogether.

We don't really have dialogues. And opening a debug profile subview would only confuse the user.

How can I play with them in the editor? I mean, what buttons should I press? I'd prefer to play around with them before trying to portray them.

Its the last button on the scene toolbar, but it only has "No icon yet" icons and no functionality yet. So far we only have a partial object editing mode (and a pathgrid editing mode that is not ready for merging) and both are not connected to the button at this point.

I had to downplay the "play" sign because it attracted too much attention.

I still believe the best way to indicate that the action is impossible is to use the system's insensitive button. I've smoothed out the borders of the image to emphasize the button itself and make its state (sensitive/insensitive) more visible.

As for the "play" button, I strongly suggest to make it the last icon in the panel, here's why:

1) Currently you seem to have the block of togglebuttons interrupted by a regular button, which is somewhat confusing. Moving the play button to the end would create a contiguous block of toggebuttons.

2) People generally read vertical toolbars (or just about anything vertical) top to bottom. A layout [view toggles - try it button - editing toggle] is not the order you'd use those elements in. You'd rather set up the view, then edit something, then try it in-game - which gives [view toggles - editing toggle - try it button].

Please try it and let me know if you think a different icon for the insensitive state is necessary.